Electrolytic process and product.



UNITED STATES PATENT OFFICE.

CLINTON PAUL TOWNSEND, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR T0ELMER A. SPERRY, OF BROOKLYN, NEW YORK.

ELECTROLYTIC PROCESS AND PRODUCT.

Specification of Letters Patent.

Patented Oct. 1, 1907.

Application filed April 24,1905. Serial No. 257,273. 7

from the commercial monoxid of lead as heretofore known.

If a solution of sodium acetate or other alkali metal salt which iscapable of yielding a solvent for lead' at the anode by electrolyticdecomposition be electrolyzed between electrodes of lead, a solution ofacetate or other salt of lead is formed at the anode, while at thecathode the hydroxid of the alkali metal is produced in equivalentquantity. This alkali metal hydroxid reacts with the lead salt to form awhite amorphous precipitate of lead hydroxid, the sodiiim acetate orequivalent salt employed as an electrolyte being simultaneouslyregenerated.-

I have discovered that by suitably modifying the above conditions acharacteristic crystalline product may be obtained, said productconsisting substantially of lead oxid, PbO, instead of the hydrateobtained as above described. A preferred mode of carrying out theprocess is as follows: An electrolytic cell having an anode of lead andany suitable cathode is subdivided by a diaphragm which is substantiallyimpermeable as a filter. The diaphragm may conveniently consist ofparchment paper, and the cathode compartment may advantageously be ofrelatively small capacity.- The anolyte-consists initially of a solutionof sodium acetate of convenient concentration: the initial catholyte maybe sodium acetate, water, or preferably a solution of sodium hydroxid..In any case sodium hydroxid accumulates in the cathode compartment untila defi- 1 appear in the anolyte, these crystals or crystallineaggregates having usually the form of thin plates having oppositereentrant angles.

The lead anode dissolves substantially in accordance with the currentand its surface remains free from an adherent deposit. sired, wherebythe potential difference for a given our- The solution may be heated ifde- Portions of the electrolyte carrying the yellow crys- I tallineproduct in suspension may be withdrawn continuously from the 'cell, thecrystals separated by a filter press or by suitable settling andseparating devices, and the clear solution returned to the cell. Theproduct may then bewashed with water and dried at about 100 C. The dryproduct so obtained is found to consist substantially of lead and oxygenand tocorrespond substantially to the formula PbO. It is to a slightextent acted upon by water with the formation of lead hydroxid, and theproduct, after washing with Water and drying at 100 C. as abovedescribed, usually yields small proportions of moisture upon ignition.Small quantities of carbon dioxid are also usually evolved.

The product of the electrolysis consists initially of thin plates asabove described, and although crystalline isvery smooth to the touch.The product dried at coniparatively low temperature, as 100 0.,possesses peculiar physical properties, especially inthat it darkensrapidly under the influence of light and that the crystalline platesinitially formed are subject to rapid disintegration. The product isfurther characterized by its tendency to hydrate in presence of water,acids or salts, a property which is highly advantageous as rendering itvery quickly soluble even in dilute acids: in this respect it is sharplydistinguished from ordinary litharge.

If the crystalline product be heated to a temperature considerably above100 0., and preferably to low redness, it is found to differ in severalimportant respects from the product dried at 100 C. and to approach morenearly in properties the monoxid of lead as heretofore known; thus it isno longer darkened by exposure to light, and it exhibits little or notendency to become hydrated in presence of water or aqueous solutions.It

dissolves readily, however, in the usual solvents for and tosimultaneously regenerate the electrolyte in ac-' I do not limit myselfto the use of a diaphragm as above described nor to the particularsolutions or conditions above mentioned as suitable.

The essential feature of the process consists in effecting a reactionbetween two compounds of lead, the lead constituting the base of onecompound and constituting a part oi the acid radical of the othercompound.

By suitably modifying the concentration oi the solutions and otherconditions the oxid of lead may be obtained informs other than theyellow crystalline plates above described; for instance, I have thusbeen able to obtain a red precipitate consisting of minute aggregates ofnearly spherical form, I do not, therefore, limit the process toconditions under which the lead oxid is produced-in any particularphysical form.

I claim:

1. The method of producing lead oxid which consists in decomposing asuitable electrolyte with an anode of lead and producing compounds inwhich lead occurs in the basic and acid radicals respectively, andeffecting a reaction be tween said compounds, substantially asdescribed.

2. The method of producing lead oxid which consists in decomposing analkali-metal acetate solution with an anode of lead and producingcompounds in which lead occurs in the basic and acid radicalsrespectively, and effecting a reaction between said compounds,substantially as described.

3. The method of producing lead oxid which consists in passing anelectric current from an anode of lead through a suitable electrolyteand diaphragm and producing compounds in which lead occurs in the basicand acid radicals respectively, and efiecting a reaction between saidcompounds, substantially as described.

4. The method of producing lead oxid which consists in passing anelectric current from an anode of lead through an alkali-metal acetatesolution and producing compounds in which lead occurs in the basic andacid radicals respectively, and elfecting a reaction between saidcompounds, substantially as described.

5. The method of producing lead oxid which consists in passing anelectric current from an anode of lead through an alkaltmetal acetatesolution and diaphragm and producing compounds in which lead occurs inthe basic and acid radicals respectively, and effecting a reactionbetween said compounds, substantially as described 6. The method ofproducing lend oxid, which consists in efiecting a reaction betweencompounds in which lead oc curs in the basic and acid radicalsrespectively, substantially as described.

7. The method of producing lead oxid, which consists in eifecting areaction between a plumbiie and a soluble salt of lead, substantially asdescribed.

8. The method of producing lead oxid, which consists in efiecting areaction between a pluinbite and lead acetate, substantially asdescribed.

9. The method of producing lead oxid which consists in passing anelectric current from an anode of lead through a suitable electrolyte,and causing the anode and cathode products to react under suchconditions as to produce lead oxid, substantially as described.

10. The method of producing lead oxid which consists in passing anelectric current from an anode of lead through a suitable electrolyteand diaphragm, and permitting the cathode product to return to theregion of the anode at such rate as to produce lead oxid, substantiallyas described.

11. The method ofprodueing lead oxid, which consists in electrolyticallydissolving lead and precipitating lead monoxid, substantially asdescribed.

12. The method of producing lead oxid, which consists inelectrolytically dissolving lead, precipitating lead monoxid, andheating the precipitate, substantially as described.

13. The herein described electrolytic product consisting substantiallyof lead and oxygen in atomic proportions, ex isting initially as yellowcrystals, darkening by exposure to light, and readily hydrated.

14. The herein described electrolytic product consisting substantiallyof lead and oxygen in atomic proportions, existing initially as yellowcrystalline plates haw ing opposite reentrant angles, darkening byexposure to light, and readily hydrated.

Witnesses:

EUGENE A. Brnwns, JULIA B. HILL.

